The present invention relates to a hydrogen station, a method for charging hydrogen, and a vehicle, and more particularly, to a technique suitable for quickly charging hydrogen into a hydrogen tank installed in a vehicle.
Recently, people have become more conscious of the need for suppressing global warming. Thus, hydrogen-fueled automobiles using hydrogen as fuel, such as fuel cell electric automobiles and hydrogen automobiles, have been developed. A typical hydrogen-fueled automobile is provided with a hydrogen tank that is charged with hydrogen gas and functions as a hydrogen supply source.
The use of metal referred to as “hydrogen adsorption alloy” has been given attention as a method for storing and transporting hydrogen. Hydrogen adsorption alloy adsorbs hydrogen and becomes a hydride under certain temperature and pressure conditions and releases hydrogen when necessary under different temperature and pressure conditions. A hydrogen tank using hydrogen adsorption alloy has been given attention since it can store more hydrogen with the same volume than a hydrogen tank that does not use hydrogen adsorption alloy.
The hydrogen gas is filled into a hydrogen tank at a hydrogen station, which is a facility equivalent to a gas station or an LP gas station. The hydrogen station includes, for example, a hydrogen cylinder assembly provided with a plurality of cylinders, and a dispenser (charger) for charging hydrogen supplied from the hydrogen cylinder assembly into the hydrogen tank of a vehicle. A coupler arranged at the distal end of a hose of the dispenser is coupled to a charging port of the hydrogen tank. In this state, the pressure difference produced between the hydrogen cylinder assembly and the hydrogen tank charges hydrogen gas into the hydrogen tank.
The temperature in the hydrogen tank rises when charging hydrogen gas into the hydrogen tank. Thus, the hydrogen tank must be cooled during the charging. Otherwise, much time becomes necessary for the charging of hydrogen. Further, when increasing the charging amount of hydrogen by having the hydrogen adsorption alloy adsorb hydrogen, hydrogen adsorption reaction occurs and causes an exothermic reaction. Thus, the hydrogen adsorption alloy must be cooled so that the hydrogen adsorption reaction occurs smoothly.
As a hydrogen supply system suitable for a hydrogen fueled automobile equipped with a hydrogen tank using hydrogen adsorption alloy, a hydrogen station provided with a coolant supply system for supplying the hydrogen tank with coolant to cool the hydrogen adsorption alloy in the hydrogen tank has been proposed (for example, refer to Japanese Laid-Open Patent Publication No. 7-108909). A hydrogen fueled automobile includes a coolant circulation system through which coolant for cooling the engine is circulated. When supplying the hydrogen gas from the hydrogen tank to the engine, the coolant in the coolant circulation system that has been heated after cooling the engine is used to heat the hydrogen adsorption alloy. In addition to the coolant circulation system, the hydrogen supply system includes a pipe for supplying coolant to cool the hydrogen tank when charging hydrogen gas into the hydrogen tank and a pipe for discharging the coolant.
However, in the hydrogen supply system described in Japanese Laid-Open Patent Publication No. 7-108909, a passage for the flow of a heat medium that heats the hydrogen adsorption alloy when hydrogen is being released from the hydrogen adsorption alloy, and a passage for the flow of the coolant that cools the hydrogen adsorption alloy when adsorbing the hydrogen to the hydrogen adsorption alloy must be separated in the hydrogen tank. Thus, the structure of the hydrogen tank becomes complex and the hydrogen tank becomes large.
The applicant of the present application has proposed the following system as a heating/cooling system for a fuel cell automobile provided with a hydrogen tank using hydrogen adsorption alloy. Specifically, in the system, a heat medium that has cooled the fuel cell is used as the heat medium for heating the hydrogen adsorption alloy when releasing the hydrogen from the hydrogen adsorption alloy. Further, the same heat medium used as the heat medium for heating the hydrogen adsorption alloy is used as the heat medium for cooling the hydrogen adsorption alloy when the hydrogen adsorption alloy adsorbs hydrogen. In this system, the heat medium is cooled by a radiator installed in the fuel cell automobile. During the operation of the fuel cell, the hydrogen adsorption alloy is heated by the heat medium that has cooled the fuel cell and the heat medium is then cooled by the radiator. In this case, the cooling of the fuel cell and the heating of hydrogen adsorption alloy are performed in a satisfactory manner. However, when the hydrogen adsorption alloy adsorbs hydrogen, that is, when charging a large amount of hydrogen (e.g., 5 kg) into the hydrogen tank under a high pressure (e.g., 35 MPa) within a short period of time (e.g., within 5 min.), the heat generated by the hydrogen adsorption alloy and the heat generated by the compression of the hydrogen gas cannot be sufficiently released by just cooling the heat medium with a normal vehicle radiator and fan. The value of 5 kg for the charging amount of the hydrogen is the value required for the fuel cell automobile to travel 500 km, which is about the same as a gasoline fueled automobile, with a single hydrogen charging.
When charging hydrogen under an environment in which the ambient temperature is 30° C. while cooling the heat medium with a normal vehicle radiator and fan, with the radiator having a coolant flow rate of 60 L/min and the fan producing a maximum current velocity of 2 m/s, only about 85% of the 5 kg, that is, only 4.25 kg of hydrogen can be charged in five minutes when the hydrogen tank is empty. In order to charge 95% (4.75 kg) or more of the 5 kg of hydrogen in five minutes, the current velocity produced by the fan must be 6 m/s or higher. However, to use a fan capable of producing such current velocity in a fuel cell automobile, a large installation space is required. Further, the fan has surplus capability at times other than hydrogen charging.
If an outlet and an inlet are provided for the heat medium in a heat medium circulation passage formed in a fuel cell automobile and when charging hydrogen into the hydrogen tank at a hydrogen station, a heat medium cooling passage of the hydrogen station is connected to the outlet and the inlet of the heat medium circulation passage of the fuel cell automobile to cool the heat medium at it circulates in the hydrogen station. However, there is usually more than one type of heat media and the heat medium usually differs between manufacturers. Thus, heat media must be prepared at a hydrogen station in accordance with the various types of heat media used in fuel cell automobiles. Further, when charging hydrogen, the connection of the heat medium circulation passage to the heat medium coolant passage is burdensome.